Fire alarm



J. C. GIBSON May 22, 1962 FIRE ALARM Filed Jan. 24, 1958 S TA TIONS CEA/TAAL ALARM SMT/ON 10 ALARM 77 HOA/v 21 P/Lo LAMP INVENTOR. Jefferson C. Gibson United States Patent Office 3,636,294 Patented May Z2, 1362 aesazat FIRE ALARM Jelferson C. Gibson, 217 E. Cullerton, Chicago, Ill. Filed Jan. 24, 1958, Ser. No. 710,957 4 Claims. (Cl. 340-227) The present invention relates to fire alarm systems and particularly to a lire alarm system including a central alarm station and a plurality of monitoring substations.

An object of the present invention is a simple and inexpensive lire alarm system of the type described wherein the central alarm station and the substations are continuously energized and wherein responsive to an abnormal temperature condition in any one of the substations, the central alarm station is operated to render both a visual and an audible alarm.

Another object of the invention is to provide thermostatic means at each of the substations which is adjustable to be responsive to different alarm temperature and which when operated in response to an abnormal temperature condition is maintained operative thereafter despite gradient changes in the temperature from the abnormal temperature.

A feature of the invention is an improved re alarm circuit provided with pilot lamps at the central station and at each of the substations illuminated under normal conditions of operation to indicate the monitoring state of the central station and of the` substations.

An additional feature of the invention is the provision in each of the substations of a conductive bimetallic thermostat arrangement adjustable for different temperature ranges and which includes a magnetized Contact plate completing a circuit with the temperature flexed bimetallic thermostat and maintaining such circuit in spite of gradient temperature changes tending to interrupt the circuit contact.

Another feature of the invention is the inclusion in the central alarm station circuit of a normally energized gravity solenoid which when deenerg-ized completes a circuit for operating alarm devices.

Further objects and features of the invention pertain to the particular structure and arrangement employed in the invention whereby the above described objects are attained. The invention, both as to its structure and mode of operation, will be better understood by reference t the following specification and drawings, forming a part thereof, wherein:

FlGUREl is a circuit diagram in schematic form of the re alarm system;

FIGURE 2 shows in detail the structure of and the .circuit connections in each of the substations of the fire alarm system;

FIGURE 3 shows in partial cross-section the structure of a gravity solenoid that may be employed in the circuit of the central alarm station; and

FIGURE 4 shows in partial cross-section the structure of a spring loaded solenoid that may be employed in the circuit o-f the central alarm station.

Referring now to the drawings, there is shown in FIG- URE l a lire alarm system in accordance with the invention including a central alarm station and a plurality of monitoring substations including the substation 3l?. The central alarm 'station 1t) includes an alarm lamp 13, a step-down transformer 14, a pilot lamp 18, an alarm horn 19 and a solenoid relay 40 and a solenoid relay 70. AEach of the substations such as the substation 30, includes a bimetallic thermostat 31, a magnetic contact 32 for the thermostat 31, and a pilot lamp 33.

Considering in detail the structure of the central alarm station 10, a 110 volt, 60 cycle source is applied to the primary winding 14a of the transformer 14 through conductors 11 and 12 and is extended in multiple from the conductors 11 and 12 to the alarm lamp 13 through conductors 44 and 48 and the normally closed contacts of the solenoid 40, here represented schematically by contacts 21. The secondary winding 14b of the step-down transformer 14 is center tapped and a circuit is completed from the center tap 51 via a conductor 15 through the pilot lamp 1S and a conductor 17 extending to a terminal end 52 of the winding 14h. In addition, a connection is completed from the terminal end 52 through the conductor 17, the alarm horn 19, a conductor 2), the winding of the solenoid relay 49, a conductor 21 and a conductor 16 to the other end terminal 53 of the secondary winding 14h. In this circumstance and without considering further connections frorn the central alarm station to the substations, the current flows between the center tap 51 and the end terminal 52 of the secondary winding 14b through the pilot lamp 18 thereby illuminating the lamp and a current ows between the terminals 52 and 53 of the secondary winding 14b in series through the alarm horn 19 and the winding of the solenoid relay 40. The solenoid 40 is energized in order to maintain the operating circuit for the alarm lamp 13 interrupted at the contacts 21, and the impedance of the energized solenoid is such that the current flow through the series connected alarm horn 19 is insuicient to operate the horn. Accordingly, in this circumstance, the pilot lamp 18 of the central alarm station 10 is illuminated to indicate that the central alarm station is in monitoring operation and neither the alarm lamp 13 or the alarm horn 19 are operative.

rIhe solenoid relay which, as schematically illustrated in FIG. l includes the contacts 71, is connected across the secondary winding 14h to conductors 16 and 17, respectively, by conductors 73 and 72 so that the relay is energized and the contacts 71 are opened. A circuit including a conductor 75, a battery source 77, contacts 71 and a conductor 74 is connected across alarm horn 19 at conductors 17 and 2t) for energizing the alarm horn when the solenoid relay 70 is deenergized and the contacts 71 are closed as by a power failure to the step-down transformer 14. In the circuit a switch 76 may -be included for intermpting the circuit and preventing operation of the alarm horn 19.

Considering now the connection of the substations such as the substation 30 to the central alarm station 10, a conductor 22 is connected in multiple to the substations at the junction between the conductors 21 and 16 in the central alarm station and a conductor 23 is connected in multiple to the substations from the conductor 20 in the central alarm station. In the substations, as in the substation 30, a pilot lamp 33 is connected in series between the conductors 22 and 23, and in parallel with the lamp 33 is the normally opened circuit including the bimetallic thermostat 31 and the magnetic contact 32. The magnetic contact 32 is coated or plated with silver, copper, or the like to render it highly conductive. Under normal temperature conditions, the circuit between the bimetallic thermostat 31 and the magnetic contact 32 is opened so that the pilot lamp 33 is connected in parallel with the winding of the solenoid relay 40 inthe central alarm station 10. Accordingly, the pilot lamp 33 is illumina-ted, thereby indicating that the substation 30 is in monitoring operation.

Assuming an abnormal temperature condition such as would cause the bimetallic plate 31 to complete a circuit at the magnetic contact 32 in the substation 30, a low irnpedance path is'completed between the terminals 52 and 53 of the secondary winding 14b including the conductor 17, the alarm horn 19, the conductor 23, the bimetallic thermostat 31, the magnetic contact 32, conductor 22 and conductor 16. Accordingly, both the winding of the .ated to indicate that an abnormal temperature condition exists at one of the substations. The alarms will continue to operate throughout the period of the abnormal temperature condition, through gradient fluctuationsY in temperature and even after the abnormal temperature condition has been corrected and until .the contact between the bimetallic thermostat 31 and the magnetic Contact 32 is broken. Thereupon, the low impedance path is interrupted, and the path through the winding of the solenoid 40 is again completed and the alarm lamp 13 and the alarm horn 19 are both rendered inoperative. Specific operation and construction of the substation 30 will be better understood from the following considerations.

As shown in FIGURE 2, in each of the substations, 'such as the substation 30, the conductor 22 from the central alarm station is terminated on a terminal 61 common to the magnetic contact 32. The conductor 23 extending from the central alarm station 10 is terminated in the substation on a terminal 62 which is connected by means of a strap 66 to a pivotal arm 63. The arm 63 is pivotally mounted on an axis 64 and carries thereon the bimetallic strip 31 having .a curved portion 31a and 'a straight portion 31b. Also mounted on the arm 63 is the pilot lamp 33 supported at one of its terminals in a clip 65 completing a conductive connection with the arm 63 and connected at its other terminal by a conductor 67 to the substation terminal 61. In this manner a circuit is completed from the conductor 22 to the conductor 23 Y via the terminal 61, the conductor 67, the lamp 33, the

support clip 65, the arm 63, the strap 66, and the terminal 62, whereby the pilot lamp 33 is illuminated when the central alarm station 10 is provided with energizing power. The arm 63 against which the free end 31b of the bimetallic strip 31 rests under normal temperature conditions is arranged in the substation 30 with regards to brations may be provided as shown in FIGURE 2 whereby the substation'can be set to be responsive and to render an alarm at Various different temperatures here shown to extend in a range between 85 and 200. Thus,

assuming that the substation is set to`be responsive to` Y a temperature of 200 as shown in FIGURE 2 and assuming a normal temperature of approximately 70, as the temperature within the area of the substation 3 0 increases to 200 the bimetallic strip 31 is graduallydistorted-'in its portion 31a and along its straight surface to move the free end 3111 thereof towards -the magnetic contact 32. When the temperature of 200 or more is achieved, con- Vtact will have been completed between the metallic strip 31 and the magnetic contact 32 so that a circuit is completed between the conductors 22 and 23 via the terminal61, the magnetic contact 32, the bimetallic strip 31, the arm 63, the strap 66 andthe `terminal v62. VThe pilot lamp 33 is shunted and extinguished.- ',Accordingly, an alarm isV sounded at the `central alarm station 10. This circuit-is maintained completed as long as the temperathereby completing-a conductive path between the-con-V ture is above 200 and due to the magnetic attraction e of-t'nemagnetic contact32 a good Circuit connection'will remain maintained between the bimetallic strip and the magnetic contact even after the temperature in the area has dropped 1to considerably less than 200, for example, to Thus the magnetic contact insures a good circuit connection between the contact and the bimetallic strip and causes the alarm condition to persist until in all certainty the Vabnormal temperature condition has subsided.

For purposes of testing the operation of the central alarm sta-tion circuit and reproducing therein the same effects as would be created by an abnormal temperature condition at any one of the substations such as the substation 30, a test switch 78 is connected in parallel with the winding of Vthe solenoid relay 40. Upon closing of the test switch 78 a low impedance path is completed between the terminals 52 and 53 of the secondary winding 14h including the conductor 17, the alarm horn 19, the conductor 20, the contacts of the test switch 78, the conductor 21 and the conductor 16. Accordingly, the winding of the solenoid relay 40 in the central alarm station and the conductors 22 and 23 extending to the substationss are shunted so that a large current ows through the alarm horn 19 thereby causing an audible signal toV be emitted. At the same time the solenoid Yrelay 40 is deenergized thereby completing the circuit between the conductors 11 and 12 for illuminating the alarm lamp 13.

Considering the circumstance where a power failure to the central alarm station is experienced so that the alarm system is inoperative for renedring abnormal temperature alarms, provision is made for operating the alarm horn 19 without illuminating the alarm lamp 13 toindicate the power failure condition. Specifically, with a power failure the windings of the relays 40 and 70 are deenergized so that the contacts 21 and 71 are closed. Even though the contacts 21 are closed the alarm lamp 13k is not illuminated becauseof the lack of power.' However, when the contacts 71 are closed the previously described circuit including the battery source 71 is completed across the alarm horn 19 and causes operation of the alarm horn. Operation of the alarm horn 19 without illumination of the alarm light 13 indicates power failure to the attendantat the central alarm station and alerts him that the fire alarm system is ineffective until power is restored.

The structural details of the one type of solenoid relay employed in both the relay 40 and the relay 70 ofthe central alarm station 10 is shown in FIGURE 3. rThe solenoid relay structure shown therein is of the gravity Y type and includes a coil coreV 41 of insulated material joined at its ends to an insulator collar 42 and an insulator collar 43, respectively, by means of a cylindrical conductive shaft 49 extending through the coil core 41. At the collar end 42 a circuit conductor 54 is inserted intoV the cylindrical casing 49 and in conductive relationship therewith and at the collar end 43 a conductive screw or plug 47 having a circuit conductor 55 connectedrthere# to is inserted'in spaced apart relationship with the, cylin-V dition the circuit between the conductor 54 and ther con-` Y ductorV 55 is incomplete.

energized, the solenoid pin 46 drops from its proximate c When the winding 50 is derelationship to the conductor 54 and rests on ,the plug.47

ductor 54 andthe Vconductor 55 v-ia the cylindnircal casing 49, the solenoid pin 46 and the conductive plug 47. Y

An alternative structure for the solenoidrelays 40V and assegna 70 employed in the central alarm station 10 is shown in FIG. 4. The solenoid relay thereof is of a spring loaded type and includes all of the structural elements of the -relay shown in FIG. 3 and in addition a helical spring 56. In this arrangement a circuit is completed between conductors 54 and 55 by action of the spring engaging the pin 46 against the plug 47. However, when the winding 50 thereof is energized, the pin 46 is withdrawn from Contact with the plug 47 and the spring 46 is compressed as shown in FIG. 4 thereby interrupting the circuit between the conductors 54 and 55.

As previously explained, the windings of the solenoid relays 40 and 70 are normally maintained energized so that the circuits controlled thereby are normally incomplete. In the case of relay 70, the winding thereof is deenergized in response to a power failure to the central alarm station so that the contacts 71 are closed and the circuit completed for operating the alarm `horn 19. In the case of relay 40, the winding thereof is deenergized in response to operation of the test switch 78 or an abnormal temperature condition in one of the substations so that the contacts 21 thereof are closed and the circuit completed for operating the alarm horn 19 and illuminating the alarm lamp 13. It is to -be understood that the alarm lamp 113 is merely illustrative of a group of alarm devices operative from the relay 40 and that fire doors, alarm sirens, remote indicators, etc. could also be operated under control of the relay 40.

In view of the foregoing, there -has been provided herein an improved lire alarm system of simple and inexpensive construction. Though the embodiment described herein is at present considered to be preferred, it is understood that variations and modifications may be made therein and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is claimed is:

1. A fire alarm system operative from a rst source of power, a visual alarm device, a first solenoid relay including a conductive solenoid pin connected in a series circuit with said visual alarm device and said first source of power to complete a conductive path responsive to the non-energization of said first relay, an audible alarm device of an impedance low as compared to the winding of said relay, a second source of power, a second solenoid relay including a conductive solenoid pin connected in a series circuit with said audible alarm device and said second source of power to complete a conductive path through said audible alarm device responsive to non-en* ergization of said second relay, a transformer including a primary winding connected to said first source of power and a secondary winding connected in parallel with the winding of said second relay for energizing said second relay and connected in series with the winding of said second relay and said audible alarm device wherein a substantial portion of the power in said series connection is utilized in said second relay winding to energize and to operate said second relay so that said audible alarm ldevice is not operative, and temperature responsive means operative for completing a conductive path shunting the winding of said second relay and of an impedance low as compared to that of said audible alarm device, wherein responsive to the operation of said temperature responsive means a series conductive path is completed through said temperature responsive means and said audible alarm device and the secondary winding of said transformer and a substantial portion of the power in said path is utilized in said audible alarm device and said second relay is shunted and deenergized and rendered inoperative, whereby said visual alarm and audible alarm devices are operated.

2. The tire alarm system set forth in claim 1 wherein said first and second solenoid relays each include a hollow cylinder of conductive material for containing said solenoid pin, an input conductor connected to said cylinder, and an output conductor spaced apart from said conductive cylinder, said solenoid pin being dimensioned and positioned so that responsive to energization of the relay said solenoid pin is retracted into said conductive cylinder and responsive to non-energization of the relay, said solenoid pin is extended from said cylinder and completes conductive contact between said cylinder and said output conductor.

3. The fire alarm system as set forth in claim 2 wherein each of said iirst and second solenoid relays is of the gravity type wherein responsive to non-energization of the relay the solenoid pin falls into conductive contact with said output conductor.

4. The tire alarm system as set forth in claim 2 wherein each of said lirst and second solenoid relays is of the spring loaded type wherein responsive to non-energization of the relay the solenoid pin is pressed into conductive contact with said output conductor.

References Cited in the tile of this patent UNITED STATES PATENTS 651,325 Dorsey June 5, 1900 1,146,637 Massa July 13, 1915 1,729,137 Stalmach Sept. 24, 1929 1,780,202 Martin Nov. 4, 1930 2,044,256 Nothstine June 16, 1936 2,300,092 Baum Oct. 27, 1942 2,736,012 Bland et al. Feb- 21, 1956 2,745,926 Mullally May 15, 1956 2,753,548 Gates July 3, 1956 

